Color tube convergence system deflecting beam in two directions with single magnet



Nov. 5, 1968 SHIGEYA ASHIZAKI ET AL 9 COLOR TUBE CONVERGENCE SYSTEMDEFLECTING BEAM IN TWO DIRECTIONS WITH SINGLE MAGNET Original Filed Dec.14, 1964 2 Sheets-Sheet 1 FIG. l2 PR/Of? ART INVENTORS $0155 yaAlli/29k! ATTORNEYS Nov. 5, 1968 SHIGEYA ASHIZAKI ET AL 3,409,791

COLOR TUBE CONVERGENCE SYSTEM DEFLECTING BEAM IN TWO DIRECTIONS WITHSINGLE MAGNET Original Filed Dec. 14, 1964 2 Sheets-Sheet 2 INVENTORS ms5; M312 mam #nnu Irma/1:

BY WMM ATTORNEYS United States ABSTRACT OF THE DISCLOSURE A shadowmask-type color image tube comprising three electron guns in anevacuated envelope with one gun being provided with a pair of horizontaldeflecting pole pieces and a pair of vertical deflecting pole piecesmade of ferromagnetic material. Magnetizing means are arranged outsideof the envelope to magnetize both the pair of horizontal deflecting polepieces and the pair of vertical deflecting pole pieces. The magnetizingmeans comprises only one magnet so mounted that the magnetic lines offorce of the magnet act on both pairs of deflecting pole pieces.

This application is a continuation of application Ser. No. 417,860,filed Dec. 14, 1964, now abandoned.

This invention relates to cathode-ray tube devices, and moreparticularly to improvements in or relating to those ofmultielectron-gun type in which electron beams emitted from a pluralityof electron guns are converged onto any minute area on the fluorescentscreen.

The primary object of the present invention is to provide a cathode-raytube device in which the horizontal and vertical deflecting pole piecesprovided for one of a plu- I rality of electron guns can be magnetizedby a single common magnet disposed outside the cathode-ray tube, wherebyelectron beams emitted from the electron guns are converged onto anyminute area on the fluorescent screen.

There are other objects and particularities of the present invention,which will be made obvious from the following detailed description, withreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of the essential parts of a conventionalthree-electron-gun cathode-ray tube;

FIG. 2 is a similar view of a cathode-ray tube embodying the presentinvention.

FIG. 3 is a partial end view of a cathode-ray tube in accordance withthe present invention, and

FIG. 4 is a perspective view of a portion of a cathoderay tube inaccordance with the present invention.

Generally speaking, in a cathode-ray tube comprising a plurality ofelectron guns, such as color television receiver tube ofthree-electron-gun type, all the electron beams emitted from respectiveelectron guns should be converged onto any minute area on thefluorescent screen.

In order to enable such convergence as above-described, ferromagneticdeflecting pole pieces as shown in FIG. 1 have heretofore been providedfor electron guns.

In particular, each of three electron guns 1, 2 and 3 has a Y-axisdeflecting pole pieces 4, 5 or 6 secured to the forward end of theelectron gun,in order to converge the elecron beams emitted fromrespective electron guns, and at the same time, the focussing electrode7 of one electron gun, say 1, is provided with X-axis deflecting polepieces 8 for effecting deflection in the direction perpendicular to theabove. To these pole pieces magnetic fields of appropriate strengths aresupplied from outside the tube by means of magnets 9 through 12,respectively, correspOnding to deflecting pole pieces 4, 5, 6 and 8forming substantially four independent magnetic circuits.

Consequently, two of the three electron guns are provided with pairs ofY-axis deflecting pole pieces 5 and 6 only, respectively, but theremaining electron gun I is provided with two pairs of deflecting polepieces, that is, Y-axis deflecting pole pieces 4 and X-axis deflectingpole pieces 8. As a result, in order to supply appropriate strength ofmagnetic fields to both deflecting pole pieces 4 and 8, there arerequired two independent magnets 9 and 12, and in addition, the relativeminute adjustment of these magnets is extremely complicated to effect,with considerable skill.

The present invention has succeeded to eliminate such disadvantages asabove.

Referring now to FIG. 2, three electron guns 21, 22 and 23 of thecathode-ray tube embodying the present invention, are provided withY-axis deflecting pole pieces 24, 25 and 26, respectively, at theirforward ends, these pole pieces, per sc, being of known construction andfunction.

According to the present invention, one of these elec tron guns, say 21,is provided with X-axis deflecting pole pieces 27 which are arrangedadjacent to the Y-axis deflecting pole pieces 24 coaxially therewith. Asa result, while it is necessary to provide two magnets 28 and 29 forsupplying magnetic fields to magnetize the Y-axis deflecting pole pieces25 and 26 respectively, a single magnet 30 can be co-used for supplyingmagnetic field to energize both of the Y-axis deflecting pole pieces 24and X- .axis deflecting pole pieces 27, because of the fact that, whenthe turning of magnet 30 about its axis 31 and the shift of the same inthe axial direction of the tube as well as in the directionperpendicular thereto are effected simultaneously, the relativestrengths of magnetic field components supplied to the deflecting polepieces 24 and 27 vary continuously, and consequently, the electron beamis deflected in the direction of resultant vector of the two componentsof magnetic field, that is the field in the pole pieces 24 and 27. Thatis to say, the electron beam emitted from the electron gun 21 can thedeflected in every direction in appropriate degree.

As has been understood from the foregoing description, according to thepresent invention, one of a plurality of electron guns, that is providedwith horizontal and vertical deflecting pole pieces, is supplied withmagnetic field from a single magnet for magnetizing and controlling bothof the deflecting pole pieces, by virtue of the fact that they aredisposed adjacently to each other, and the electron beams emitted from aplurality of electron guns, respectively, can well be converged onto anyminute area on the fluorescent screen. Thus, according to the presentinvention, such an advantage is obtained as to simplify the convergenceadjustment in color television receiver tube.

The present invention is particularly advantageous when practiced incolor television receiver tube employing shadow mask, but may also beapplied to multielectrongun cathode-ray tubes of other types andcathode-ray tubes for measurement, for effecting adjustment andconvergence of electron beams.

What is claimed is:

1. In a cathode-ray tube device comprising an evacuated envelope havinga face plate on one end thereof, three electron guns mounted in saidenvelope to direct three converging electron beams at said face plate, amask grid having a large number of minute openings and positionedbetween said electron guns and said face plate for bombardingpredetermined areas on said plate with electron beams from said electronguns, a group of minute openings and positioned between said electronguns ner surface of said face plate forming color triads at particularpositions defined by the relation between said electron guns and saidmask grid, a pair of horizontal deflecting pole pieces and a pair ofvertical deflecting pole pieces aligned with the beam path of one ofsaid electron guns, said pairs of horizontal and vertical deflectingpole pieces being formed of ferromagnetic material and being disposedadjacent to each other for adjusting the electron beam of the associatedelectron gun, and a single magnet movably mounted outside of saidenvelope for feeding flux adjustable in amount and direction to bothpairs of horizontal and vertical deflecting pole pieces, each said polepiece having a flux receiving surface adjacent said magnet wherebymagnetic fields are produced to deflect said electron beam in adirection which is the resultant vector of said magnetic fields.

2. A cathode-ray tube device according to claim 1 in which the remainingtwo electron guns, other than said one electron gun provided with pairsof both horizontal and vertical deflecting pole pieces, are respectivelyprovided with only a single pair of deflecting pole pieces fordeflecting the electron beam of the associated electron gun in a singledirection.

3. A cathode-ray tube device according to claim 1 in which said singlemagnet is mounted for at least one of the following movements: shiftingin the direction axially of the tube; shifting in the directionperpendicular thereto; and rotation about an axis perpendicular to atube axis and passing through the center of said magnet.

4. In a cathode-ray tube device comprising an evacuated envelope havinga face plate on one end thereof, three electron guns mounted in saidenvelope each directing an electron beam to converge on said face plate,a mask grid having a large number of minute openings and beingpositioned between said electron guns and said face plate for bombardingpredetermined areas on said face plate with said electron beams, a groupof minute areas of red, green and blue light emitting phosphors disposedon the inner surface of said face plate at particular positions definedby the relation bet-ween said electron guns and said mask grid, at leastone of said electron guns being provided with a pair of horizontal and apair of vertical deflecting pole pieces disposed adjacent to each otherand in alignment with the electron beam of said gun, said pole piecesbeing formed of ferromagnetic material, and a single magnet disposedoutside said envelope, each said pole piece having a flux receivingsurface adjacent said magnet whereby flux from said magnet magnetizesboth said pairs of horizontal and vertical deflecting pole piecesprovided for said one of said electron guns to deflect the electron beamin adirection which is the resultant vector of the magnetic fieldproduced.

5. In a cathode-ray tube device comprising an evacuated envelope havinga faceplate on one end thereof, first, second and third electron gunsmounted in said envelope to direct their electron beams to converge onsaid face plate, a mask grid having a large number of minute openingsandpositioned between said electron guns and said face plate for bombardingpredetermined areas of said face plate with the electron beams from saidelectron guns, a group of minute areas of three kinds of phosphors forproviding red, green and blue light rays, respectively, disposed on theinner surface of said face plate at particular positions defined by therelation between said electron guns and said mask grid, said firstelectron gun being provided with a pair of horizontal deflecting polepieces and a pair of vertical deflecting pole pieces, both pairs ofdeflecting pole pieces being fonrned of ferromagnetic material, saidpairs of deflecting pole pieces being disposed adjacent to each otherfor adjusting the electron beam of said first electron gun, a singlepair of deflecting pole pieces provided for each said second and thirdelectron guns for deflecting their associated electron beams in a singledirection, and a single magnet disposed outside said envelope formagnetizing both of said pairs of horizontal and vertical deflectingpole pieces provided for said first electron gun, each pole piece ofeach of said pairs of deflecting pole pieces having a flux receivingsurface adjacent said magnet, said single magnet being movable in atleast one of the following directions: axially of the tube;perpendicular to the axis of the tube; and rotatably about an axisperpendicular to the tube axis and passing through the center of saidmagnet whereby the magnetic flux developed is varied so that theelectron beam is defiected in a direction representing the resultantvector of the magnetic fields produced.

References Cited UNITED STATES PATENTS 2,769,110 10/1956 Obert 3l375 X2,806,164 9/1957 Clay et al 313- X 2,847,598 8/1958 Hughes 3l3702,923,844 2/1960 Gundert 31377 X ROBERT SEGAL, Primary Examiner.

